Tailstock



Oct. 2l, 1952 E. J. LoMAzzO TAILSTOCK original Filed May 18, 194e 3Sheets-Sheet 1 IN V EN TOR. Edna/z d J Lomazzo BY ww Oct. 2l, 1952 E. J.LoMAzzo TAILSTOCK 5 vSheets-Sheet 2 Original Filed May 18, 1946IIIIIIIIIIII'III l I. l I

' INVENTOR. i Z2/mmm L amazza BY grp-@MW Oct. 21, 1952 E.l J. oMAzzo2,614,447

TAILSTOCK Original Filed May 18, 1946 y 3 Sheets-Sheet 3 TOP cARRuAeE -4HEADTOCE INVENTOR. drm/nd J ZU/mz zo ATTORNEY' Patented Oct. 21, 1.952

v 'rAiLsTocK Edmund J. Loma-zzo, Norwalk, Conn., assignor to SparksMachine Tool Corporation, Norwalk, Conn., a corporation of ConnecticutOriginal application May 18, 1946, Serial No.

670,794. Divided and this application September 25, 1948, Serial No.51,288

(ci. :s2-31)" 2 Claims. l

This invention relates to a machine tool and particularly to the workholding means therefor. This application is a division of my copendingapplication Serial No. 670,794, filed May 18, 1946.

In accordance with the present invention there is provided an improvedwork holding system wherein the tailstock is provided with adjustablebearings forv taking up wear in the spindle and in which the tailstockspindle is automati-i cally moved to work engaging position with apredetermined pressure on the work, may be automatically locked in saidposition by the adjustable bearing,A and the work chucked by the chuckling means in predetermined sequence. 'A

A feature of the present invention resides in the novel manuallyoperated semiautomatic electrohydraulic system for controlling theoperation Eof 'each of the various elements of the lathe such as thehydraulic pump, the spindle drive Fig. 3 is a lfragmentary sectionalview of, a

modied tailstock.` f f Fig. 4'is va hydraulic diagram of theelectrohydraulic control system. r K

As shown in the drawings the lathe comprises a frame having endpedestals I0 and Il and a main bed I2 extending therebetween. ThepedestalY I0 has a driven work chuck I3 therein which'driven work chuckis substantiallythe same as that shown in the Sparks et al. Patent No.2,389,746. The main bed is provided With the usual ways (not shown) forslidably supporting the tailstock I4 in adjusted position therealong inwhich position it is clamped by screws I5 to support work mounted in thechuck. The bed also carries a back tool-carrying .carriage I6 which ismovable toward and away from the work and longitudinally of the work.The

pedestals I0, II carry a top frame II having a top Atool-carryingcarriage I8 thereon. The specific structure of the two carriages andtheir operation is disclosed and claimed in myjcopending application,Serial No. 51,289, filed` Sieptember 25, 1948.

The ychuck I3 is hydraulically operated in substantially the same way asin the aforementioned patent. The operating means for the chuckisillustratedjin Fig. 4 as a cylinder I9 Ahaving a piston 20 reciprocatingtherein under hydraulic pressure. The piston actuates the draw or chuckrod 2| to close and release the jaws 22 in the usual manner. y

The tailstock as shown in Fig. 2 is provided with a sliding quill 23'having a live center; 24 which is mounted in the quill on the usualroller or ball bearings (not shown) for free rotation therein. f

In practice the quill `becomes worn through continueduse `andbecomeswobbly and unsteady in the tailstock. The present invention provides abearing for the quill which will take up the Wear and, in one` form ofthe invention, provides for locking the quill in work supportingposition. Y

This bearing is in the form of a sleeve 25 surrounding the quill and inwhich the lquill is slidable.` The bearing is slidable in a bore 26 inthe tailstock frame and the quill and sleeve are held against rotationby a key 2I. The sleeve has at its forward end' a split section 28forming bearing fingers 29 which cooperate with a cam ring 30 secured inan enlargement 3| of the bore at the front of the tailstock frame sothat the end of the bearing fingers are inwardly deflected by the camring to engage and support the quill and take up any wear therebetween.

In the form of the invention shown in Fig. 2 the take-up is automaticand the bearing fingers perform the additional function of automaticallylocking the quill in work supporting position. Inaccomplishing this,thequill is provided with a bore 32 at the back end which is closed bythe plate 33 and forms the cylinder 34 in which is'mounted a piston 35having a piston rod 36 passing through the plate and fixed to thebearing sleeve 25. The sleeve is normally urged into the forwardposition in which the bearing fingers are relieved of pressure againstthe quill by means of a spring 31 surrounding the sleeve and having oneend bearing on the shoulder 38 on the sleeve and the other end engagingthe adjusting nut 39 threaded into the tailstock frame as shown in Fig.2 and locked by a set screw 40.

The piston rod has two conduits 4 I, 42 therein. Conduit 4I passesthrough the piston and into the head of the cylinder and conduit 42opens into the rod end of the cylinder. When pressure'f is applied toconduit 4 I, the `Iviuid enters the cylinder and acts against thev frontwall to move thev quill and center forward into engagement with thework. When the quill is stopped by engagement with the work, pressurebuilds up in the cylinder and acts on the piston and moves it and thebearing sleeve backward against the action of the spring until thebearingkngers are tightened about the quill and not only hold it againstlateral play but also against longitudinal movement.

A feature of the invention resides in the fact that the pressure of thecenter against the work can be readily regulated by adjusting thetensionin the spring by means ofl theadj'usting nut 35. With the pressure thusregulated danger of jamming or damaging the bearings by undue pressureon the center is eliminated for the quill will always be locked inposition in which the pressure on the work is only that, necessaryV tosequence valve (as .hereinafter f described) to ,v

operate and connect pressure to the rod end of the chucking cylinder ISwhich causes the piston to move the chuck jaws 22 intoworkhcldingposition and maintain them in said position.

i When it is. desired torelease the holding means the pressure isapplied to thehead end or" the chucking cylinder causing the piston. 2lito move the chucking jaws to be released and also pressure is applied totheconduit i2 in the. piston rodl and the rod endof cylinder `35.. Thispressure, since the quill is held stationary, will cause the piston tomove forwardly drawing the bearing sleeve with it and releasing thebearing fingers from locking engagement. with the quill. Thereafter, thequill cylinder will move back readily and out of engagement with thework.

If it is desired the hydraulic iluid may be used to lubricate thetailstock spindle mechanism. As shown in Figs. 2 and l two conduits 43,44 are extended through the tailstock frame into the oilreceivinglgrooves disposed about the sleeve. A solenoid .controlled valve 4G,connected in the electrical circuit for actuating, theholding means,will connect the conduitsto the pressure line momentarily during theoperation of the chucking button (not shown) for closing of the chuck`ing circuit to give a squirt of fluid to the spindle for each operationvthereof as will be more fully explained in connection with theelectrohydraulic circuits. l

I r" the locking feature is not required the bearing sleeve may bemounted in the tailstock frame for adjustment longitudinally therein tocause thebearing fingers to be moved along the cam ring and intoengagement with the quill to tal-:e up any play which might occur. Thisadjustment may be made in many ways, for example in Fig. 3 the tailstockbore 2S is threaded at 4l and the sleeve 25 is threaded at 58. A nut 49is rotatable' on the 'sleeve and threaded into the tailstock frame and anut threaded on the sleeve vclamps theV nut against a shoulder 5l on thesleeve.' When it is desired to take up wear', nut 55 is loosened and awrench is applied tothe portion 52 of the nut l5 and it is turned todraw the sleeve back and move the ngers in. Then the nut is tightenedand locks the sleeve inrposition.

In operating the work holding means the tail stock quill and center isfirst moved into engage ment with the work and thereafter the chuck isoperated to grip the Work and hold the work until the operations havebeen completed and an unchucking operation is manually initiated. Thecomplete hydraulic system for the machine and its operation aredisclosed and claimed in my abovefmenticned copending. applicationSerial 150.6705554;

The operating circuit is shown diagrammatically in Fig. 4 in neutralposition. The motor 52 driving the pump 53 is energized and the pumpdelivers fluid under pressure to all operating parts ci the system.

Thev workpiece may now be placed in the machine between.- y the chuckand the tailstock center and a circuit closed through the chuck buttonswitch (notshown) to solenoid 54 forming a part of. the hydraulic workholding valve 55.

Referring now to the hydraulic circuit diagram (Fig. ll) theenergization of solenoid 54 actuates the pilot valve 56 of holding valve55 to admit .fluid pressure to` the left end of valve spool- 51 and moveit to the right-hand position.. This connects the main pressure port 58of valve 55 to a line leadingv to a pressure reducing.v valve 59 and, bymeans of a branch line, to a sequence valver S5. Valve 6B is alsoconnected by aline to a second pressure reducing valveil.v The springsetting of, sequence valve 6B is such, however, that uid pressure iirstflows through the valve 59 at reducedpressure, tothe head end oi. thetailstock quill cylinder,. through conduit 4I. which, because the pistonis in a xed position. moves the quill to the left causing they tailstockcenter to engage the `work and push it into the chuck. Exhaust iiuidfrom the, rod end of the quill cylinder passes through conduit 42 toWork holding valve 55 and thenceto tank.

As the work. comes to its nal, position in the. chuck the pressurebuilds up in the quill cylinder. and serves to move the bearing sleeve25 to lock the same in operating positionashereinbefore describd. Afterthe quill is thusv automatically locked, the built-up pressure thenbecomes sui-"ii,- cient to move the spool 52 of the seqi'iencel .valve60 to the left thus connecting its pressureport to a line leading to thesecond pressure reducing valve 6l. Fluid at reducledpressure then now-sthrough valve 6l direct .to the rod end of the chuck operating cylinderlll,A moving its piston v2) to the left and, by means of the draw orchuck rod 2l projecting through the spindle. actuating: the chuck jaws22 to gripA the workpiece.

As the chuck jaws 22 reach their final positionthe further building upof the pressurey in :the chuck cylinder to a predetermined value servesto operate, through a branch line, a pressure switch 63 connected in theelectrical control circuite@ of the spindle drive motor which is nor,-mally open. Until this switch is closed, by pressure in `excess of thatrequired to rigidly hold the workpiece, the spindle cannot be rotated.lExhaust iiuid from the head endof thev chuck cylinderrlg passestoholding valve 55 and to tank.

The workpiece is now securely held in position for the cutting operationand cannot be released until the circuit throughsolenoid 54 is opened tounchuck the work.

When it is desired to remove afinished workpiece, the operator breaksthe circuit to solenoid 54 on holding valve 55. v

As solenoid 54 is deenergized the pressure port of associated pilotvalve 56 is closed and the line from the left end of spool 51 isconnected to a.

tank line thus allowing the spool to move to its left-hand positionunder influence of its associ-n ated spring. The left-hand position ofspool 51 work permitting it to be removed from the mav chine. Exhaustfluid from the head end of the tailstock quill cylinder 34 passesthrough the piston to tank via lines to pressure reducing valve 59 whereit is by-passed freely over the lower check valve contained therein, andthence through valve 5,5. Exhaust uid from the rod end of chuck cylinderI9 passes to pressure reducing valve 6|, where it is freely by-passedover the lower check valve contained therein, thence to sequence Valve60, and then to and through valve 55 to tank. As this latter hydrauliccircuit from the chuck cylinder is connected to tank the pressure inthis line drops and permits pressure switch 63 `to open in preparationfor the next work cycle.

When the4 feature of lubricating the tailstock spindle is incorporatedin the machine whereby lubrication of the tailstock mechanism isautomatically accomplished at regular operating intervals the two-way,solenoid controlled valve 49 is provided having its pressure portconnected directly to a hydraulic pump pressure line and its solenoid46av electrically connected in the chuck control circuit in such a waythat every time vchuck starting buttom lis depressed the solenoid 46a isenergized and momentarily opens the hy` draulic pressure port of valve46 to a line leading to the tailstock lubricating system and thus.delivers a shot of oil to the system.

Variations and modifications may be made within the scope of thisinvention and portions of the improvements may be-used without others.

I claim:

1. In a machine tool having work holding means including a tailstockframe provided with a movable tailstock spindle carrying a work engagingcenter and means for locking the spindle 6 in work engaging position;and hydraulic means for moving the center into engagement with the workwith a predetermined pressure including adjustable means on the exteriorof the tailstock for varying said pressure, said adjustable meansincluding an annular nut surrounding the taill stock spindle andthreaded to the tailstock frame.

2. In a machine tool having work holding means including a tailstockframe provided with a `movable tailstock spindle carrying a workengaging center and adjustable bearing means for the spindle; andhydraulic means included a pisn ton connected to the bearing meansoperative in a cylinder in the spindle to move the center intoengagement with the work with a predetermined pressure and thetreafteradjust the bearing means to take-up for wear between the bearing vandspindle, said bearing means comprising a sleeve having a portion ofreduced outer diameter forming a forward shoulder, a spring surroundingand supported by said portion and having one end abutting said shoulder,and an adjustable abutment comprising an annular member surrounding thesleeve and threaded to the tailstock frame and engaging the other end ofthe spring to vary the tension in said spring and said predeterminedpressure, said adjustable abutment having a portion extending to theexterior of the tailstock whereby adjustments thereof can be madewithout dismantling the tailstock.

EDMUND J. LOMAZZO.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 651,381 Peters June 12, 19001,162,794 Magnuson Dec. 7, 1915 1,408,837 Soholewski Mar. 7, 19221,834,831 Drummond Dec. 1, 1931 2,140,565 Svenson Dec. 20, 19382,389,746 Sparks Nov. 27, 1945

